Don't Give EAB a Ride!

Posted by: Denyse Schrenker, Eagle County Extension

People were seeing fireworks last week when it was confirmed that emerald ash borer has made its way to the Western Slope. Two new pockets of emerald ash borer (EAB) in Littleton and Carbondale were recently discovered. These new locations are well outside of the known infested area north of Denver: see Colorado State Forest Service map for known EAB locations. In case you missed it, Emerald Ash Borer is an invasive insect that feeds under the bark of trees during its larval stage. This feeding stops the flow of nutrients and water and gradually kills the tree over a 3 to 5 year timespan. All true ash species (Fraxinus spp.) are hosts for EAB. Green ash (Fraxinus pennsylvanicus) and white ash (Fraxinus americana) are commonly grown in Colorado and both are highly susceptible to emerald ash borer, including their cultivars such as the popular white ash variety, ‘Autumn Purple Ash’. Mountain-ash (Sorbus spp.) are not susceptible to emerald ash borer as they are not a true ash.

Damage from emerald ash borer. Photo credit: Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org

How is this different from mountain pine beetles?
Although mountain pine beetle has killed a large number of trees as well, it is a native insect that has periodic outbreaks. The outbreaks are a naturally occurring cycle (though they can be prolonged by human activity) that will eventually end and the surviving trees will regenerate the forest over time. Since emerald ash borer is not native to North America it has no native predators to halt outbreaks so it will continue as long as there are ash trees present.


What Can I Do?

White ash tree. Photo credit: Richard Webb, Bugwood.org

Don’t Move Firewood (remind your friends & family too!)
With camping season in full swing, don’t be tempted to save a couple bucks by taking firewood with you. Always burn firewood locally and buy seasoned and kiln-dried wood as many harmful insects, not just EAB, can hitch a ride in firewood. You can learn more about this at https://www.dontmovefirewood.org/.

Use firewood locally, emerald ash borer and other harmful insects can hitch rides in firewood.

Use Best Tree Care Practices

• Watering Mature Trees
• Watering Your Landscape During a Drought
• Fall and Winter Watering 
• Mulching Trees 
• Healthy Roots, Healthy Trees

Learn to Identify Ash Trees

• Ash Tree Identification
• Contact your local extension office for assistance with identification

White ash leaf. Photo credit: Paul Wray, Iowa State University, Bugwood.org

Learn More about Emerald Ash Borer

• Emerald Ash Borer Resources
• Colorado State Forest Service: Emerald Ash Borer
• FactSheet: Recognizing Wood Boring Insects of Ash Trees in Colorado

Emerald ash borer in exit hole. Photo credit: Debbie Miller, USDA Forest Service, Bugwood.org

Make a Plan

If you are in close proximity to an outbreak, start making a plan for your ash trees. Contact your local extension office for more information.